Scotland's top prosecutor has supported a change in the law to allow the Crown to appeal certain criminal cases if they are thrown out of court.
Elish Angiolini took questions from MSPs on the issue
Lord Advocate Elish Angiolini made a statement to parliament on the collapsed World's End murder trial.
She said that, hypothetically, such a right of appeal would have been used.
A judge dismissed the case against convicted killer and rapist Angus Sinclair, who was accused of murdering two teenage girls 30 years ago.
Sinclair, 62, denied killing 17-year-olds Christine Eadie and Helen Scott 30 years ago in what became known as the World's End case.
During the trial, judge Lord Clarke said the Crown had insufficient evidence to proceed.
The two girls were last seen in the World's End pub in Edinburgh and their bodies were found dumped in East Lothian.
Ms Angiolini told MSPs she was disappointed that the case had not reached a jury, while insisting there was enough evidence to bring a case.
She said: "In my view, this evidence which was provided by the Crown, established a circumstantial case against Angus Sinclair."
Labour justice spokeswoman Margaret Curran claimed the families in the case had been let down by the criminal justice system.
She urged the lord advocate to make representations to ministers on the Crown's right to an appeal - which it currently does not have in such cases.
Ms Angiolini said it was not for her to set the goalposts, but added: "I have, however, expressed my concern about the absence of such a right of appeal for the prosecutor in Scotland at that particular stage and indeed raised that matter with the minister for justice some weeks ago - not in the context of any particular case."
Nationalist MSP Nigel Don also questioned the lord advocate on whether she would have appealed.
The girls were last seen alive at the World's End pub
The lord advocate said: "Given that this is a hypothetical situation, it's difficult to speculate on that basis, but clearly from what the Crown submissions were, at the conclusion of the Crown case and given what I've said about sufficiency, it would have been a case where the Crown would have appealed in such a circumstance, had the right existed."
Ms Angiolini denied the case had not been prosecuted properly and, answering criticisms that the Crown did not present some DNA evidence found on the underwear of both victims, said it was "low probability".
She added that the lawyer who led the World's End prosecution, Alan Mackay, who went missing but was later found safe and well, had made an "outstanding contribution" to the prosecution of crime.
The Lord Advocate also disclosed that prosecutors had previously considered the possibility of Sinclair being responsible for the murder of four other young women in Glasgow in 1977.
But in those cases, she said, there was no DNA evidence, no confession, and no direct evidence to implicate him.